Glastonbury organisers have tried to end speculation that Jay-Z is considering pulling out of his headlining slot at this year's festival, claiming that the negative reaction to his appearance at the event is "hysterical".

Emily Eavis, who runs the festival with her father, Michael, admitted she had "thrown a curve ball" to traditional festivalgoers. "Jay-Z is one of the biggest, most respected hip-hop artists in the world," she said, adding that he is reputed to have turned around the way black music is perceived in America. "[Black music] really was bling," she said. "And he came along, and him and Mary J Blige carried really important messages in songs. They're really important in a different way to a lot of other hip-hop artists. People might not expect him, but we have a responsibility to do something a bit different."

While Eavis rubbished tabloid reports that the rapper would pull out of the event, she admitted that the cold response to his appearance in Somerset had rattled the performer's camp. "I think his team are thinking: what's going on here? What is this reaction?"

She added: "We have lost some fairweather friends, yes. We've made a bit of a curveball decision. But we feel we've made a really important decision and we're absolutely going to stick by it because we think it's going to be amazing."

Born Shawn Carter, Jay-Z, 38, rose from a humble upbringing in the New York projects to become the "richest man in hip-hop", thanks to a business empire that has included a record label, a multimillion-dollar clothing label and a line in property development.

Alex Miller, editor of the NME's new bands section, said Jay-Z had a unique appeal to a generation of fans. "Why wouldn't you want to watch the best rapper of the last decade roll through a greatest hits package on a stage surrounded by the world's coolest pop stars?"

But others have been less enthusiastic about a festival that has been beset with troubles. Many of last year's record 177,000 attendees complained that, not for the first time, persistent rain turned the Somerset fields that host the event into an unpleasant mud bath. That led to travel problems, as coach drivers refused to pick up people stranded for hours in the mud. There were also complaints that the festival had lost its magic, and that a ticket registration process designed to combat touts had rendered the festival demographic older and more affluent, with people perhaps more keen to have a barbecue than lose themselves for 72 hours.

Organisers point out that there will be nine other stages for those not keen on the rapper. A full line-up is expected to be announced next month, but Goldfrapp, Leonard Cohen, the Editors, Panic at the Disco, Jimmy Cliff and The Cribs are among the bands known to have signed up, along with fellow headliners Kings of Leon and the Verve.